Quick answers
| Question | Answer | Scope | Source | Checked |
|---|---|---|---|---|
| Do they hibernate? | No. They slow down a lot and spend most of the winter inside their lodges, living on food stored in the pond. | North American beaver, Bering Land Bridge page | NPS, Bering Land Bridge National Preserve | |
| What they eat | Plants only. They eat the inner bark of trees, not the wood. At Yellowstone, willow and aspen are the preferred winter foods. | North American beaver, Bighorn Canyon and Yellowstone pages | NPS, Bighorn Canyon National Recreation Area; NPS, Yellowstone National Park | |
| How long they live | Yellowstone gives an average of 5 years. Bighorn Canyon says they can live to 20. | North American beaver, Yellowstone and Bighorn Canyon pages | NPS, Yellowstone National Park; NPS, Bighorn Canyon National Recreation Area | |
| How big they get | 35–40 inches long including the tail, and 30–60 pounds. | North American beaver, Yellowstone page | NPS, Yellowstone National Park | |
| Family groups | Related families called colonies. At Yellowstone a colony has 2–14 beavers, six on average. | North American beaver, Yellowstone page | NPS, Yellowstone National Park | |
| Babies | Kits, born April to June, two to four to a litter. They stay with their parents until age 2, then leave to build their own homes. | North American beaver, Bering Land Bridge page | NPS, Bering Land Bridge National Preserve | |
| How long they stay underwater | Up to 15 minutes at a time, helped by a second, clear set of eyelids. | North American beaver, Bering Land Bridge page | NPS, Bering Land Bridge National Preserve | |
| Dams and lodges | Built from trees and branches. Some dams run over a quarter mile, and lodges have underwater entrances. | North American beaver, Bighorn Canyon page | NPS, Bighorn Canyon National Recreation Area |
In the sources’ own words
Do they hibernate?
National Park Service, Bering Land Bridge National Preserve, Beaver“Although beavers don’t hibernate through the winter, they become much less active and spend most of the winter months in their cozy lodges.”
“Beavers also use ponds and wetlands to stash their food during winter months.”
Scope: North American beaver, Bering Land Bridge page
What they eat
National Park Service, Bighorn Canyon National Recreation Area, Beavers“Beavers don’t eat wood, they eat the inner bark on trees.”
National Park Service, Yellowstone National Park, Beaver“The resulting ponds and flooding help create an environment favorable to willow and aspen, the beavers’ preferred winter foods and used in building their lodges.”
Scope: North American beaver, Bighorn Canyon and Yellowstone pages
How long they live
National Park Service, Yellowstone National Park, Beaver“Average life span: 5 years.”
National Park Service, Bighorn Canyon National Recreation Area, Beavers“Beavers can live to be 20 years old and grow to weigh 75 lbs.”
Scope: North American beaver, Yellowstone and Bighorn Canyon pages
How big they get
National Park Service, Yellowstone National Park, Beaver“35–40 inches long, including tail.”
“Weighs 30–60 pounds.”
Scope: North American beaver, Yellowstone page
Family groups
National Park Service, Yellowstone National Park, Beaver“Like wolves, beavers live in family groups, which are called colonies.”
“One colony may support 2–14 beavers that are usually related.”
“Six is considered average.”
Scope: North American beaver, Yellowstone page
Babies
National Park Service, Bering Land Bridge National Preserve, Beaver“Beaver young, known as kits, are born between April and June in litters of two to four.”
“They live with their parents until they reach 2-years-old, when they venture out to build their own homes.”
Scope: North American beaver, Bering Land Bridge page
How long they stay underwater
National Park Service, Bering Land Bridge National Preserve, Beaver“A second set of transparent eyelids allows them to navigate underwater for up to 15 minutes at a time.”
Scope: North American beaver, Bering Land Bridge page
Dams and lodges
National Park Service, Bighorn Canyon National Recreation Area, Beavers“Trees and branches are used for building dams some of which are over a quarter mile long, and for constructing their lodges complete with underwater entrances.”
Scope: North American beaver, Bighorn Canyon page
What these sources do not say
- How fast beavers swim.